• Journal of Environmental Science International
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• v.20 no.5
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• pp.581-587
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• 2011

Industrial natural ventilation systems consist of gravity ventilator, the high/low windows and doors. Especially, the high windows play an important role in the industrial natural ventilation systems. Generally speaking, industrial high windows are divided into 3 types; louver type, $45^{\circ}$ open type and $90^{\circ}$ open type. This study was numerically and experimentally conducted. Three types of windows were tested to know the ventilation characteristics and estimate the ventilation efficiencies. Numerically, computational fluid dynamics software (AIR PAK Ver. 2.0) was used to observe the flow characteristics inside the industrial building and the concentration contours generated by the tracer gas method. Experimentally, the flow visualization technique and the tracer gas method were applied with the model building to characterize the flow pattern inside the model building and to estimate the ventilation efficiencies with the different windows. It was found that $90^{\circ}$ open type window was most effective for the discharge of pollutants from the industrial building. On the other hand, the louver type window was found to be less effective than any other windows.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.324-330
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• 2015

The electrolyte flow rates of vanadium redox flow battery play very important role in terms of ion transfer to electrolyte, kinetics and pump efficiency in system. In this paper a vanadium redox flow battery single cell was tested to suggest the optimization criteria of electrolyte flow rates on the efficiencies. The compared electrolyte circulation flow rates in this experimental work were 15, 30 and 45 mL/min. The charge/discharge characteristics of the flow rate of 30 mL/min was the best out of all flow rates in terms of charging and discharging time. The current efficiencies, voltage efficiencies and energy efficiencies at the flow rate of 30 mL/min were the best. The IR losses obtained at thd current density of $40mA/cm^2$, at the flow rates of 15, 30 and 45 mL/min were 0.085 V, 0.042 V and 0.115 V, respectively. The charge efficiencies at the current density of $40mA/cm^2$ were 96.42%, 96.45% and 96.29% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The voltge efficiencies at the current density of $40mA/cm^2$ were 77.34%, 80.62% and 76.10% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. Finally, the energy efficiencies at the current density of $40mA/cm^2$ were 74.57%, 77.76% and 73.27% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The optimum flow rates of electrolytes were 20 mL/min in most of operating variables of vanadium redox flow battery.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1233-1239
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• 2016

This study aimed to evaluate changes in the TN and TP removal efficiencies, depending on whether or not a settling process is applied, in a sequencing batch reactor (SBR) process with a membrane bioreactor (MBR). Nutrient removal was considered in terms of developing an advanced water treatment system for ships in accordance with water quality standards set forth by 227(64). For these purposes, the TN and TP concentrations in the inflow and outflow water were measured to calculate the TN and TP removal efficiencies, depending on whether or not a settling process was used. Water discharged from a bathroom, which was constructed for the experiment, was used as the raw water. The experiment that included a settling process was conducted twice, and the operating conditions were: aeration for 90 min, settling for 30 min, agitation for 15 min, and settling for 15 min for one experiment; and aeration for 150 min, settling for 45 min, agitation for 15 min, and settling for 15 min in the other. Operating conditions for the experiment that did not include a settling process were: aeration for 180 min and agitation for 60 min. The concentration of the mixed liquor suspended solids (MLSS) in the reactor was 3,500 mg/L, while the aeration rate was 121 L/min and the water production rate was 1.5 L/min. For the two experiments where a settling process was applied, the average TN removal efficiencies were 44.39% and 41.05%, and the average TP removal efficiencies were 47.85% and 46.04%. For the experiment in which a settling process was not applied, the average TN removal efficiency was 65.51%, and the average TP removal efficiency was 52.51%. Although the final nutrient levels did not satisfy the water quality standards of MEPC 227(64), the TN and TP removal efficiencies were higher when a settling process was not applied.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1953-1961
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• 2014

Increasing public concerns over odors and air regulations necessitates the remediation of a wide range of odor substances for industrial and indoor purpose. Currently, the wet scrubbing technique by neutralization using oils is being used to treat odor substances such as Ammonia($NH_3$), Methyl Mercaptan($CH_3SH$), Hydrogen Sulfide($H_2S$), Methylamine($CH_3NH_2$), Acetaldehyde($CH_3CHO$). The chemical analysis is performed to analyze the composition of an Arctium Lappa Root extract by VOC analyzer(Phocheck 5000Ex, ION SCIENCE co.) The objectives of the this study are to clarify the possibility of the neutralization of odors sprayed in the fixed bed and determine the removal efficiencies for different input odor concentrations. It is found that Ammonia($NH_3$), Methyl Mercaptan($CH_3SH$), Hydrogen Sulfide($H_2S$), Methylamine($CH_3NH_2$), Acetaldehyde($CH_3CHO$) are significantly removed and their removal efficiencies are higher than 98%. The kitchen detergent with Arctium Lappa Root extract showed excellent removal efficiencies of odor substances and high possibility for the development of kitchen detergent with odor removal.

• Proceedings of the Korean Environmental Health Society Conference
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• 2003.06a
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• pp.162-165
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• 2003

Uptake efficiencies of PCB 153 in fathead minnow through food chain of sediment-midge-fish were evaluated. Contaminated fish food, the midge Chironomus plumosus was prepared by exposing to sediments with PCB 153. We could harvest the midges with body PCB 153 levels of ∼ 1.0 mg/g and ∼ 10.0 mg/g, respectively, in 2 wk of exposure. PCB 153 level in fish fed with midge of 10.0 mg/g PCB 153 (high-dose group) reached its highest at 11.2 mg/g after 30 d of exposure. However, PCB level in fish fed with midge of 1.0 mg/g PCB 153 (low-dose group) kept increasing following first order rate kinetics until the end of exposure (38 d). When the fish food was changed to the uncontaminated ones, the fish body PCB levels were stabilized in ∼ 3 wk. The uptake efficiency in high-dose fish group was 37%, whereas low-dose group was 55%. Uptake efficiencies in fathead minnows were notably lower than that of pike (∼ 70%). This finding suggests that the uptake efficiency of this PCB congener may depend on the amount of the PCB in diet.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.692-697
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• 2015

In this study, the reduction efficiencies of leachate heavy metal levels were investigated by adding $Al_2O_3$ and CaO to the bottom ash to observe their effects on the heavy metals leachate reduction efficiency. The ratio of $Al_2O_3$ and CaO contents were varied by 10~40% (W/W) alongside different curing time of 7 and 28 days. The reduction efficiencies of leachate heavy metal levels were estimated to be 69.3% for Cu and 52.1% for Pb during the curing time of 7 days. For the curing time of 28 days, the efficiencies changed to 85.2 and 100% for Cu and Pb, respectively. It was thus confirmed that the high reduction efficiency could be obtained as the curing time increased.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.653-657
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• 2014

Effects of $H_2O_2$ addition for fenton oxidation on iron coagulation for treatment of phosphorus species, such as orthophosphate, metaphosphate, pyrophosphate, organic phosphate, were investigated. The effects of coagulant dosage, hydrogen peroxide dosage and the combined sequence ferric coagulation and $H_2O_2$ addition for fenton oxidation and coagulation were studied. The characteristics of floc growth rate were monitored using the PDA. The removal efficiencies of phosphorus species by iron coagulation were increased as Fe/P molar ratio increased. However, the removal efficiencies of metaphosphate, pyrophosphate, organic phosphate by a ferric coagulation were not increased as Fe/P molar ratio increased. The removal efficiency of metaphosphate, pyrophosphate, organic phosphate was increased by using iron coagulation and $H_2O_2$ addition for fenton oxidation. The result indicated that non-reactive phosphorus after iron coagulation was changed to reactive phosphorus by $H_2O_2$ addition for fenton oxidation and the oxidized iron enhanced the coagulation efficiencies.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.103-115
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• 1996

The purpose of this study was to establish acceptable criteria for the design of simple water treatment plant in rural areas. To develop efficient simple water treatment methods for rural areas, water quality in the study areas was investigated and rapid and slow filtrations in pilot-scale were tested under various conditions. The main results of this study are as follows. It was found that the water qualities of the study areas exceed the drinking water standards, which implies that some treatments are required in rural areas. Treatment efficiencies of both rapid sand and dual-media (sand and anthracite) filtration without pre-treatment such as flocculation and sedimentation are very low, which were turned out to be unadequate for the rural areas. Treatment efficiencies of both vertical and horizontal slow filtration without chlorination are very high for consumed $KMnO_4, NH_3-N, NO_3-N$, turbidity, and very low for coliform and bacteria. Treatment efficiencies of both vertical and horizontal slow filtration with chlorination are very high over the most pollutants. A slow filtration with chlorination is efficient for the rural areas. An adequate depth of sand layer is over 60 cm. A horizontal filtration is more economical than a vertical filtration. A horizontal filtration can be operated for a relatively long periods of time without sand washing or replacement because clogging is removed by simple back-washing.

• Environmental Engineering Research
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• v.19 no.2
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• pp.151-155
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• 2014

This study compares the effects of flow on oil and suspended solids removal efficiencies in circular enhanced gravity plate separator equipped with coalescence medium. Coalescence medium acts to capture rising oil droplets and settling solid particles and assist in the coalescence of oil and coagulation of solid. The circular separator uses an upflow center-feed perforated-pipe distributor as the inlet. The co-current flow is achieved using 4 increasing sizes of frustum, whereas cross flow uses inclined coalescence plates running along the radius of the separator. The different arrangement gave the cross flow separator a higher coalescence plan area per operational volume, minimal and constant travelling distance for the oil droplets and particles, lower retention time, and higher operational flowrate. The cross flow separator exhibited 6.04% and 13.16% higher oil and total suspended solids removal efficiencies as compared to co-current flow.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.70-76
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• 1999

A laboratory experiment was performed to investigate the phosphorus removal using the activated sludge-electrolysis reactor which consisted of A$^2$/O system and aluminium electrodes as cathode and anode. In this system, the phosphorus was removed by aluminium ion, which was eluted from aluminiumelectrodes by electrolysis. In the batch experiments, when the current densities were 0.026, 0.052 and 0.08 A/dm$^2$, the phosphorus removal efficiencies for synthetic sewage were 66.4, 86.4 and 98.7% respectively. These results showed that the phosphorus removal efficiency increased with the increase of the current density. When the current values were 13, 26 and 40 mA respectively, the amounts of Al$^{3+}$ eluted from electrodes according to Faraday's law were 0.049, 0.07 and 0.12 g and Al/P mole ratio were 1.1, 2.0 and 3.41. In the continuous experiments, As hydraulic retention time(HRT) increased, COD and total nitrogen(T-N) removal efficiencies for domestic sewage increased. The average phosphorus removal rates of the activated sludge-electrolysis system were 97, 91, 80 and 80% at the HRT of 48, 24, 18 and 12 hours, respectively. Especially, the phosphorus removal rate in the activated sludge system with aluminium electrodes was higher than that in the system without aluminium electrodes.